crypto/dsa/dsa_ossl.c

   1 /* crypto/dsa/dsa_ossl.c */
   2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
   3  * All rights reserved.
   4  *
   5  * This package is an SSL implementation written
   6  * by Eric Young (eay@cryptsoft.com).
   7  * The implementation was written so as to conform with Netscapes SSL.
   8  *
   9  * This library is free for commercial and non-commercial use as long as
  10  * the following conditions are aheared to.  The following conditions
  11  * apply to all code found in this distribution, be it the RC4, RSA,
  12  * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
  13  * included with this distribution is covered by the same copyright terms
  14  * except that the holder is Tim Hudson (tjh@cryptsoft.com).
  15  *
  16  * Copyright remains Eric Young's, and as such any Copyright notices in
  17  * the code are not to be removed.
  18  * If this package is used in a product, Eric Young should be given attribution
  19  * as the author of the parts of the library used.
  20  * This can be in the form of a textual message at program startup or
  21  * in documentation (online or textual) provided with the package.
  22  *
  23  * Redistribution and use in source and binary forms, with or without
  24  * modification, are permitted provided that the following conditions
  25  * are met:
  26  * 1. Redistributions of source code must retain the copyright
  27  *    notice, this list of conditions and the following disclaimer.
  28  * 2. Redistributions in binary form must reproduce the above copyright
  29  *    notice, this list of conditions and the following disclaimer in the
  30  *    documentation and/or other materials provided with the distribution.
  31  * 3. All advertising materials mentioning features or use of this software
  32  *    must display the following acknowledgement:
  33  *    "This product includes cryptographic software written by
  34  *     Eric Young (eay@cryptsoft.com)"
  35  *    The word 'cryptographic' can be left out if the rouines from the library
  36  *    being used are not cryptographic related :-).
  37  * 4. If you include any Windows specific code (or a derivative thereof) from
  38  *    the apps directory (application code) you must include an acknowledgement:
  39  *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
  40  *
  41  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
  42  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  43  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  44  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  45  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  46  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  47  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  48  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  49  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  50  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  51  * SUCH DAMAGE.
  52  *
  53  * The licence and distribution terms for any publically available version or
  54  * derivative of this code cannot be changed.  i.e. this code cannot simply be
  55  * copied and put under another distribution licence
  56  * [including the GNU Public Licence.]
  57  */
  58
  59 /* Original version from Steven Schoch <schoch@sheba.arc.nasa.gov> */
  60
  61 #include <stdio.h>
  62 #include "cryptlib.h"
  63 #include <openssl/bn.h>
  64 #include <openssl/dsa.h>
  65 #include <openssl/rand.h>
  66 #include <openssl/asn1.h>
  67 #include <openssl/engine.h>
  68
  69 static DSA_SIG *dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa);
  70 static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp);
  71 static int dsa_do_verify(const unsigned char *dgst, int dgst_len, DSA_SIG *sig,
  72                   DSA *dsa);
  73 static int dsa_init(DSA *dsa);
  74 static int dsa_finish(DSA *dsa);
  75 static int dsa_mod_exp(DSA *dsa, BIGNUM *rr, BIGNUM *a1, BIGNUM *p1,
  76                 BIGNUM *a2, BIGNUM *p2, BIGNUM *m, BN_CTX *ctx,
  77                 BN_MONT_CTX *in_mont);
  78 static int dsa_bn_mod_exp(DSA *dsa, BIGNUM *r, BIGNUM *a, const BIGNUM *p,
  79                                 const BIGNUM *m, BN_CTX *ctx,
  80                                 BN_MONT_CTX *m_ctx);
  81
  82 static DSA_METHOD openssl_dsa_meth = {
  83 "OpenSSL DSA method",
  84 dsa_do_sign,
  85 dsa_sign_setup,
  86 dsa_do_verify,
  87 dsa_mod_exp,
  88 dsa_bn_mod_exp,
  89 dsa_init,
  90 dsa_finish,
  91 0,
  92 NULL
  93 };
  94
  95 const DSA_METHOD *DSA_OpenSSL(void)
  96 {
  97         return &openssl_dsa_meth;
  98 }
  99
 100 static DSA_SIG *dsa_do_sign(const unsigned char *dgst, int dlen, DSA *dsa)
 101         {
 102         BIGNUM *kinv=NULL,*r=NULL,*s=NULL;
 103         BIGNUM m;
 104         BIGNUM xr;
 105         BN_CTX *ctx=NULL;
 106         int i,reason=ERR_R_BN_LIB;
 107         DSA_SIG *ret=NULL;
 108
 109         if (!dsa->p || !dsa->q || !dsa->g)
 110                 {
 111                 reason=DSA_R_MISSING_PARAMETERS;
 112                 goto err;
 113                 }
 114         BN_init(&m);
 115         BN_init(&xr);
 116         s=BN_new();
 117         if (s == NULL) goto err;
 118
 119         i=BN_num_bytes(dsa->q); /* should be 20 */
 120         if ((dlen > i) || (dlen > 50))
 121                 {
 122                 reason=DSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE;
 123                 goto err;
 124                 }
 125
 126         ctx=BN_CTX_new();
 127         if (ctx == NULL) goto err;
 128
 129         if ((dsa->kinv == NULL) || (dsa->r == NULL))
 130                 {
 131                 if (!DSA_sign_setup(dsa,ctx,&kinv,&r)) goto err;
 132                 }
 133         else
 134                 {
 135                 kinv=dsa->kinv;
 136                 dsa->kinv=NULL;
 137                 r=dsa->r;
 138                 dsa->r=NULL;
 139                 }
 140
 141         if (BN_bin2bn(dgst,dlen,&m) == NULL) goto err;
 142
 143         /* Compute  s = inv(k) (m + xr) mod q */
 144         if (!BN_mod_mul(&xr,dsa->priv_key,r,dsa->q,ctx)) goto err;/* s = xr */
 145         if (!BN_add(s, &xr, &m)) goto err;              /* s = m + xr */
 146         if (BN_cmp(s,dsa->q) > 0)
 147                 BN_sub(s,s,dsa->q);
 148         if (!BN_mod_mul(s,s,kinv,dsa->q,ctx)) goto err;
 149
 150         ret=DSA_SIG_new();
 151         if (ret == NULL) goto err;
 152         ret->r = r;
 153         ret->s = s;
 154
 155 err:
 156         if (!ret)
 157                 {
 158                 DSAerr(DSA_F_DSA_DO_SIGN,reason);
 159                 BN_free(r);
 160                 BN_free(s);
 161                 }
 162         if (ctx != NULL) BN_CTX_free(ctx);
 163         BN_clear_free(&m);
 164         BN_clear_free(&xr);
 165         if (kinv != NULL) /* dsa->kinv is NULL now if we used it */
 166             BN_clear_free(kinv);
 167         return(ret);
 168         }
 169
 170 static int dsa_sign_setup(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp)
 171         {
 172         BN_CTX *ctx;
 173         BIGNUM k,*kinv=NULL,*r=NULL;
 174         int ret=0;
 175
 176         if (!dsa->p || !dsa->q || !dsa->g)
 177                 {
 178                 DSAerr(DSA_F_DSA_SIGN_SETUP,DSA_R_MISSING_PARAMETERS);
 179                 return 0;
 180                 }
 181         if (ctx_in == NULL)
 182                 {
 183                 if ((ctx=BN_CTX_new()) == NULL) goto err;
 184                 }
 185         else
 186                 ctx=ctx_in;
 187
 188         BN_init(&k);
 189         if ((r=BN_new()) == NULL) goto err;
 190         kinv=NULL;
 191
 192         /* Get random k */
 193         do
 194                 if (!BN_rand_range(&k, dsa->q)) goto err;
 195         while (BN_is_zero(&k));
 196
 197         if ((dsa->method_mont_p == NULL) && (dsa->flags & DSA_FLAG_CACHE_MONT_P))
 198                 {
 199                 if ((dsa->method_mont_p=(char *)BN_MONT_CTX_new()) != NULL)
 200                         if (!BN_MONT_CTX_set((BN_MONT_CTX *)dsa->method_mont_p,
 201                                 dsa->p,ctx)) goto err;
 202                 }
 203
 204         /* Compute r = (g^k mod p) mod q */
 205         if (!ENGINE_get_DSA(dsa->engine)->bn_mod_exp(dsa, r,dsa->g,&k,dsa->p,ctx,
 206                 (BN_MONT_CTX *)dsa->method_mont_p)) goto err;
 207         if (!BN_mod(r,r,dsa->q,ctx)) goto err;
 208
 209         /* Compute  part of 's = inv(k) (m + xr) mod q' */
 210         if ((kinv=BN_mod_inverse(NULL,&k,dsa->q,ctx)) == NULL) goto err;
 211
 212         if (*kinvp != NULL) BN_clear_free(*kinvp);
 213         *kinvp=kinv;
 214         kinv=NULL;
 215         if (*rp != NULL) BN_clear_free(*rp);
 216         *rp=r;
 217         ret=1;
 218 err:
 219         if (!ret)
 220                 {
 221                 DSAerr(DSA_F_DSA_SIGN_SETUP,ERR_R_BN_LIB);
 222                 if (kinv != NULL) BN_clear_free(kinv);
 223                 if (r != NULL) BN_clear_free(r);
 224                 }
 225         if (ctx_in == NULL) BN_CTX_free(ctx);
 226         if (kinv != NULL) BN_clear_free(kinv);
 227         BN_clear_free(&k);
 228         return(ret);
 229         }
 230
 231 static int dsa_do_verify(const unsigned char *dgst, int dgst_len, DSA_SIG *sig,
 232                   DSA *dsa)
 233         {
 234         BN_CTX *ctx;
 235         BIGNUM u1,u2,t1;
 236         BN_MONT_CTX *mont=NULL;
 237         int ret = -1;
 238         if (!dsa->p || !dsa->q || !dsa->g)
 239                 {
 240                 DSAerr(DSA_F_DSA_DO_VERIFY,DSA_R_MISSING_PARAMETERS);
 241                 return -1;
 242                 }
 243
 244         if ((ctx=BN_CTX_new()) == NULL) goto err;
 245         BN_init(&u1);
 246         BN_init(&u2);
 247         BN_init(&t1);
 248
 249         /* Calculate W = inv(S) mod Q
 250          * save W in u2 */
 251         if ((BN_mod_inverse(&u2,sig->s,dsa->q,ctx)) == NULL) goto err;
 252
 253         /* save M in u1 */
 254         if (BN_bin2bn(dgst,dgst_len,&u1) == NULL) goto err;
 255
 256         /* u1 = M * w mod q */
 257         if (!BN_mod_mul(&u1,&u1,&u2,dsa->q,ctx)) goto err;
 258
 259         /* u2 = r * w mod q */
 260         if (!BN_mod_mul(&u2,sig->r,&u2,dsa->q,ctx)) goto err;
 261
 262         if ((dsa->method_mont_p == NULL) && (dsa->flags & DSA_FLAG_CACHE_MONT_P))
 263                 {
 264                 if ((dsa->method_mont_p=(char *)BN_MONT_CTX_new()) != NULL)
 265                         if (!BN_MONT_CTX_set((BN_MONT_CTX *)dsa->method_mont_p,
 266                                 dsa->p,ctx)) goto err;
 267                 }
 268         mont=(BN_MONT_CTX *)dsa->method_mont_p;
 269
 270 #if 0
 271         {
 272         BIGNUM t2;
 273
 274         BN_init(&t2);
 275         /* v = ( g^u1 * y^u2 mod p ) mod q */
 276         /* let t1 = g ^ u1 mod p */
 277         if (!BN_mod_exp_mont(&t1,dsa->g,&u1,dsa->p,ctx,mont)) goto err;
 278         /* let t2 = y ^ u2 mod p */
 279         if (!BN_mod_exp_mont(&t2,dsa->pub_key,&u2,dsa->p,ctx,mont)) goto err;
 280         /* let u1 = t1 * t2 mod p */
 281         if (!BN_mod_mul(&u1,&t1,&t2,dsa->p,ctx)) goto err_bn;
 282         BN_free(&t2);
 283         }
 284         /* let u1 = u1 mod q */
 285         if (!BN_mod(&u1,&u1,dsa->q,ctx)) goto err;
 286 #else
 287         {
 288         if (!ENGINE_get_DSA(dsa->engine)->dsa_mod_exp(dsa, &t1,dsa->g,&u1,dsa->pub_key,&u2,
 289                                                 dsa->p,ctx,mont)) goto err;
 290         /* BN_copy(&u1,&t1); */
 291         /* let u1 = u1 mod q */
 292         if (!BN_mod(&u1,&t1,dsa->q,ctx)) goto err;
 293         }
 294 #endif
 295         /* V is now in u1.  If the signature is correct, it will be
 296          * equal to R. */
 297         ret=(BN_ucmp(&u1, sig->r) == 0);
 298
 299         err:
 300         if (ret != 1) DSAerr(DSA_F_DSA_DO_VERIFY,ERR_R_BN_LIB);
 301         if (ctx != NULL) BN_CTX_free(ctx);
 302         BN_free(&u1);
 303         BN_free(&u2);
 304         BN_free(&t1);
 305         return(ret);
 306         }
 307
 308 static int dsa_init(DSA *dsa)
 309 {
 310         dsa->flags|=DSA_FLAG_CACHE_MONT_P;
 311         return(1);
 312 }
 313
 314 static int dsa_finish(DSA *dsa)
 315 {
 316         if(dsa->method_mont_p)
 317                 BN_MONT_CTX_free((BN_MONT_CTX *)dsa->method_mont_p);
 318         return(1);
 319 }
 320
 321 static int dsa_mod_exp(DSA *dsa, BIGNUM *rr, BIGNUM *a1, BIGNUM *p1,
 322                 BIGNUM *a2, BIGNUM *p2, BIGNUM *m, BN_CTX *ctx,
 323                 BN_MONT_CTX *in_mont)
 324 {
 325         return BN_mod_exp2_mont(rr, a1, p1, a2, p2, m, ctx, in_mont);
 326 }
 327
 328 static int dsa_bn_mod_exp(DSA *dsa, BIGNUM *r, BIGNUM *a, const BIGNUM *p,
 329                                 const BIGNUM *m, BN_CTX *ctx,
 330                                 BN_MONT_CTX *m_ctx)
 331 {
 332         return BN_mod_exp_mont(r, a, p, m, ctx, m_ctx);
 333 }